1. Field of the Invention
The present invention relates a section processing method and its apparatus. The invention relates to a section processing method and its apparatus of forming a section for observation by moving a processing position by successively carrying out removal processing for a sample, when for example, a defect of an inner portion of a semiconductor chip is observed.
2. Background Information
In a background art, when, for example, a failure at an inner portion of a semiconductor chip is observed, a section for observation is formed by rupturing a sample by a focused ion beam and observing the section by an electron microscope. With regard to the section for observation, for example, a position of a defect of a sample is specified by a defect inspection apparatus, and section processing is carried out based on the position information. That is, removal processing is successively repeated by irradiating a focused ion beam to a sample and a processing face is moved to a position at which a defect is present. A defect to be observed is extremely small, and therefore, at a vicinity of a position at which the defect is present, also an amount of moving the processing face is made to be small, for example, the section processing needs to be progressed while observing the processing face by a scanning electron microscope (SEM) or the like.
Further, the same goes with also a case of forming a TEM sample for observing by a transmission electron microscope (TEM).
In order to accurately and efficiently carry out the section processing, it is known to apply a mark to the sample and progress section processing while detecting a position of the mark.
As such a section processing method and its apparatus, for example, Patent Reference 1 describes a sample evaluation/processing observation system of forming two marks in a cross shape indicating an observation line constituting a center line of a TEM sample on an outer side of a region of processing the TEM sample prior to forming the TEM sample by a focused ion beam apparatus, detecting positions of the marks, and carrying out positioning or the section processing of the processing object. According to the system, the mark is formed on a non-processing face substantially orthogonal to an observation face of the TEM sample by the focused ion beam.
Further, Patent Reference 2 describes a technology in a method and apparatus of fabricating a sample of processing a sample by irradiating an ion beam to a processing face of the sample and forming a mark at a periphery of a sample processing portion for forming the mark to find out in which direction the sample processing portion is disposed in view from the mark. According to the sample fabricating method described in Patent Reference 2, in a case of fabricating a TEM sample, in a sample block constituting a processing object, marks respectively having shapes different from each other are formed in a processing face irradiated with an ion beam and a surface in a direction of observing the TEM sample, and a direction of the sample processing portion relative to the face formed with the mark is known.
[Patent Reference 1] JP-A-10-64473
[Patent Reference 2] JP-A-2005-114578
However, according to the above-described section processing method and its apparatus of the background art, the following problem is posed.
According to the technology described in Patent Reference 1, the mark is formed on the observation line on the outer side of the processing region of the TEM sample, that is, on the non-processing face substantially orthogonal to the observation face of the TEM sample, and therefore, observation of the processing face and detection of the mark position cannot simultaneously be carried out. Further, also when the mark is detected by using the focused ion beam, the mark is remote from the processing region, and therefore, it is necessary to scan a position different from the processing position or realign a focal point to respective positions, and therefore, a step separate from section processing is constituted.
Therefore, after subjecting one processing face to section processing, observation of the processing face and detection of the mark need to be carried out separately from each other, and therefore, a problem that a processing time period is increased is posed.
According to the technology described in Patent Reference 2, the mark is formed also in the direction of observing the TEM sample other than the mark provided at the processing face similar to Patent Reference 1, and therefore, although after subjecting the processing face to section processing, the mark can be observed from a direction the same as that of observing the processing face, the mark only indicates the direction of the sample processing portion, and therefore, distance information of the processing face relative to the mark provided at the processing face cannot be acquired. Therefore, with regard to whether the processing face is progressed up to a target position, the mark on the side of the processing face needs to be observed, and therefore, a problem similar to that of Patent Reference 1 is invariably posed.
The invention has been carried out in view of the above-described problem and it is an object thereof to provide a section processing method and its apparatus capable of promoting a processing efficiency of section processing.